Yes leaving it plugged and fully charged eventually reduces battery like.
The linked article basically says you should:
a) Never fully charge a Lithium-ion battery (
that makes it reach max temp),
b) Never keep it connected to AC when fully charged (
that overheats it)
Quote:
"Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling"
c) Never allow it to fully discharge or even go below 20% (
except on rare occasion) but rather keep it always with a fair level of charge. (
Discharge the battery to something like 40-70% before recharging it)
So, you should not allow the battery to fully charge to keep it as cool as possible, maybe allow it to reach 90-95% charge, and never allow it to discharge down below 20% charge and only allow it to discharge to mid charge before recharching it. Something like 40-70%
Be aware that this first link is about a drone battery but it's a lithium-ion battery so the same should apply for a laptop battery.
http
/batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
This article resumes all I said above.
https

/www.howtogeek.com/169669/debunking-battery-life-myths-for-mobile-phones-tablets-and-laptops/